1. Field of the Invention
The present invention relates to a semiconductor device photolithography processing system and a method thereof. More particularly, the present invention relates to a photolithography processing system and a method thereof that is able to detect the presence of particles remaining on a surface of a wafer during the process of forming a pattern mask and then determine a subsequent processing step for the wafer depending on the result of the detection step.
2. Description of the Related Art
In general, a semiconductor device is made by using repetitive and selective process steps, such as photolithography, etching, diffusion, chemical vapor deposition, ion implantation, metal deposition, and the like. One of the more frequently performed process steps is a photolithography process step to form a pattern mask onto the wafer.
A conventional photolithography process will now be described with reference to FIG. 1.
In a conventional photolithography processing system as shown in FIG. 1, a plurality of wafers W mounted on a carrier C are moved from a production line onto a loader 12 and then transported one by one to a desired location by a plurality of robots R1, R2, R3 of a transporter 14, which is installed on one side of the loader 12.
At this time, a first robot R1, positioned adjacent to the loader 12, takes a wafer out of the carrier C and moves it onto a first table T1, which is positioned between the first robot R1 and a second robot R2. The second robot R2 then moves the wafer W placed on the first table T1 through a pre-processing unit 16 where pre-treatment steps are performed prior to a photo-exposure process. The pre-treatment steps performed include depositing a coating liquid onto the surface of the wafer W, adding photoresist to the surface of the wafer W covered with coating liquid, heating and cooling the coating liquid and the photoresist deposited surface of the wafer and removing the remaining photoresist deposited on an edge portion of the wafer W with photo-exposure.
Then, the wafer, having been pre-treated by the aforementioned steps, is transported by the second robot R2 to a second table T2 near a photo-exposure unit 18. Next, a third robot R3, positioned adjacent to the photo-exposure unit 18, transports the wafer to the photo-exposure unit 18 for sequential steps of alignment, photo-exposure and inspection. After inspection, the third robot R3 returns the wafer W to the second table T2.
After having been through a series of processing steps after photo-exposure, the wafer is moved by the second robot R2 to a post-processing unit 20 where a series of post-treatment steps, including developing and cleaning steps, are performed. After the post-treatment steps, the second robot R2 returns the wafer W to the first table T1, which is near the loader 12, for a subsequent unloading step. During the unloading step, the first robot R1 mounts the wafer W onto a requested carrier C.
During the series of processing steps, there may be a number of impure matters, such as particles, remaining on the surface of the wafer W that has been through the series of processing steps for photo-exposure. These impure matters remaining on the wafer surface may generate defects and other faults in the process of the photoresist coating and photo-exposure steps.
As a result, the presence of impure matters increases a re-work rate of photolithography processing steps and decreases productivity. Moreover, the presence of impure matters deteriorates the quality and yield of resultant semiconductor devices.
Moreover, it is possible for the wafer W, transported through the post-processing unit 20 that performs a development step and mounted again onto the carrier C of the loader 12, to have particles remaining on the surface thereof, which become a problem by causing defects in subsequent processing steps.